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Dixon, D. A., J. Graham y M. N. Gray. "Hydraulic conductivity of clays in confined tests under low hydraulic gradients". Canadian Geotechnical Journal 36, n.º 5 (23 de noviembre de 1999): 815–25. http://dx.doi.org/10.1139/t99-057.
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Clay barriers normally function at hydraulic gradients much lower than are commonly used in laboratory tests for hydraulic conductivity. This paper describes low-gradient tests on compacted illite, Na-bentonite, and sand-bentonite specimens at a range of dry densities. The tests examined the effects of deionized or saline pore fluid, the initial degree of saturation at the time of compaction, and back-pressuring to achieve saturation during permeation. No "critical" or "threshold" gradients were observed. In low-density materials, "transitional" gradients defined two separate regions of Darcian flow. Low flow rates and low hydraulic conductivities were associated with hydraulic gradients below the transitional gradient. Higher conductivities were associated with gradients above the transitional gradient. Hydraulic conductivities decreased with increasing initial density. They appeared independent of initial degree of saturation or back-pressuring. Tests on Na-rich bentonite showed that deionized and saline permeants produced similar hydraulic conductivities. Measured hydraulic conductivities were in reasonable agreement with values computed using the Poiseuille and Kozeny-Carman equations. Key words: hydraulic conductivity, gradient, Darcian, illite, bentonite.
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Chittur K, Subramaniam, Aishwarya Chandran, Ashwini Khandelwal y Sivakumar A. "Energy Conversion using electrolytic concentration gradients". MRS Proceedings 1774 (2015): 51–62. http://dx.doi.org/10.1557/opl.2015.758.
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ABSTRACTSalinity gradient is an enormous source of clean energy. A process for potential generation from an ionic concentration gradient produced in single and multicell assembly is presented. The ionic gradient is created using a fuel cell type cell with a micro-porous ion exchange membrane, both anionic (AEM) and cationic (CEM). Various salinity gradients, Salt : Fresh, from 100 : 0 to 16000 : 0 was established using NaCl solution, in the electrode chambers. A potential of 20 mV/cm to 25 mV/cm can be realized at ambient temperatures and pressures for a bipolar AEM/CEM cell. The performance was optimized for various static and dynamic flow rates of the saline and fresh water. The cell performance can further be optimized for Membrane Electrode System (MES) morphology. A multicell unit was assembled and the results presented for various conditions like concentration gradients, flow rates and pressure. The thermodynamic and electrical efficiency needs to be evaluated for various gradients and flow rates. The relation with number of valance electrons/ ion and the potential generated changes for various dynamic condition of salinity. The higher the salinity gradient the larger is the potential generated. This is limited by the membrane characteristics. There exists a monotonic relation between the number of valence electron/ion/unit time and the potential generated up to about 16000 concentration. The membrane characteristics have been studied for optimal ion crossover for various gradients and flow. The graph between ln (gradient) versus Voltage provides insights into this process. This presents a very cost effective and clean process of energy conversion.
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KASYANOV, A. E. y ISMAIL KHEBA ISMAIL KHEBA. "INSTALLATION FOR PHYSICAL MODELING OF SALINE SOILS WASHING". Prirodoobustrojstvo, n.º 2 (2021): 31–35. http://dx.doi.org/10.26897/1997-6011-2021-2-31-35.
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Gradients of salts concentrations of the soil solution, rinsing water pressures, filtration coefficients determine the flow intensity of the salt solutions in the aeration zone. There are known a lot of software for calculating the motion of salt solutions in the porous medium. To assess the accuracy of calculations of the salts movement in the soil, the data of gradient measurements are used. The implementation of the known methods of physical modeling on the soil monoliths mounted according to Astapov, lysimetric installations, in experimental leaching of saline soils in the field requires significant material investments, labor and time. Minimum material and labor costs are required for the assembly and use of the proposed design of the installation for physical modeling of saline soil washing. A working prototype of the installation has been developed. It includes piezometers, a case, units of piezometers connection, sampling of soil moisture combined with soil electrodes, equalizing drain, rotating part of the case. Piezometers, drains and connecting hoses, soil moisture sampling unit. The installation case is assembled of separate branch pipes equipped with necks and sealing rings. Filtration investigations and gradient measurements of the salts movement are carried out on the installation. The tests of the installation prototype were fulfilled in the field on the sand pit reclamation map located in the floodplain of the Gzhelka and Moskva rivers of the Ramensk region of the Moscow area. The profile filtration coefficients measured at the installation – 2.33 ± 0.031 m / day and in the field conditions – 2.36 ± 0.041 m / day do not differ significantly.
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Scheifele, Benjamin, Rich Pawlowicz, Tobias Sommer y Alfred Wüest. "Double Diffusion in Saline Powell Lake, British Columbia". Journal of Physical Oceanography 44, n.º 11 (1 de noviembre de 2014): 2893–908. http://dx.doi.org/10.1175/jpo-d-14-0070.1.
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Abstract Powell Lake contains a deep layer of relic seawater separated from the ocean since the last ice age. Permanently stratified and geothermally heated from below, this deep layer is an isolated geophysical domain suitable for studying double-diffusive convection. High-resolution CTD and microstructure measurements show several double-diffusive staircases (Rρ = 1.6 to 6) in the deep water, separated vertically by smooth high-gradient regions with much larger density ratios. The lowest staircase contains steps that are laterally coherent on the basin scale and have a well-defined vertical structure. On average, temperature steps in this staircase are 4 mK, salinity steps are 2 mg kg−1, and mixed layer heights are 70 cm. The CTD is capable of measuring bulk characteristics of the staircase in both temperature and salinity. Microstructure measurements are limited to temperature alone, but resolve the maximum temperature gradients in the center of selected laminar interfaces. Two different algorithms for characterizing the staircase are compared. Consistent estimates of the steady-state heat flux (27 mW m−2) are obtained from measurements above and below the staircase, as well as from microstructure measurements in the center of smooth interfaces. Estimates obtained from bulk interface gradients underestimate the steady-state flux by nearly a factor of 2. The mean flux calculated using a standard 4/3 flux law parameterization agrees well with the independent estimates, but inconsistencies between the parameterization and the observations remain. These inconsistencies are examined by comparing the underlying scaling relationship to the measurements.
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Amin, Fatima, Abdul Sattar Shaikh, Sohail Khan Bangash, Amber Kamran, Nida Rafique, Mujeeb Ur Rehman y Najma Patel. "Correlation between Intraoperative Direct and Transesophageal Echocardiographic Assessment of Right Ventricular Outflow Tract Pressure Gradient in Patients Undergoing Tetralogy of Fallot Repair". Pakistan Heart Journal 56, n.º 1 (1 de abril de 2023): 92–96. http://dx.doi.org/10.47144/phj.v56i1.2484.
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Objectives: The objective of this study was to determine the correlation between intraoperative direct (needle) and transesophageal echocardiographic (TEE) assessment of right ventricular outflow tract (RVOT) pressure gradient in patients undergoing Tetralogy of Fallot (TOF) repair. Methodology: A total of 100 patients underwent for TOF repair were included. After completion of surgery and successful weaning from cardiopulmonary bypass, the TEE derived RVOT gradients were obtained from, the midesophageal ascending aortic short axis (AA Sax) view, upper esophageal aortic arch short axis (Arch Sax) view and trans-gastric RV outflow (TG RV outflow) view. Direct (needle) derived pressures from right ventricular (RV) and pulmonary artery (PA) were obtained by surgeon using a saline filled pressure transducer system. Correlation coefficient was computed between intraoperative direct and TEE assessment of RVOT gradient was evaluated. Results: In the sample of 100 patients, 41% were females and median age was 8 [5-11] years. The TEE derived RVOT gradients obtained in AA Sax, Arch Sax and TG RV outflow view were 26.46±6.98, 26.60±6.55, and 22.64±6.21 mmHg, respectively. Intraoperative RVOT pressure gradient was 19.05±8.9 mmHg. The correlation between intraoperative direct (needle) and TEE assessment of RVOT pressure gradient obtained in AA Sax, Arch Sax, and TG RV outflow view were 0.588 (p<0.001), 0.283 (p<0.001), and 0.383 (p<0.001), respectively. Conclusion: Intraoperative TEE assessment of RVOT pressure gradient showed a moderate correlation with the direct (needle) assessment. The ascending aorta short axis view was found to be the superior esophageal view.
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Niinemets, Ülo, Aljona Lukjanova, Ashley D. Sparrow y Matthew H. Turnbull. "Light-acclimation of cladode photosynthetic potentials in Casuarina glauca: trade-offs between physiological and structural investments". Functional Plant Biology 32, n.º 7 (2005): 571. http://dx.doi.org/10.1071/fp05037.
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Many arid and saline habitat species possess sparse canopies with cylindrical foliage that is considered relatively invariable along environmental gradients. However, even in sparse canopies strong gradients of light develop between the canopy top and bottom. We studied structural and photosynthetic acclimation to within-canopy light gradient in Casuarina glauca Sieb. ex Spreng., the photosynthetic organs of which are cylindrical cladodes. Seasonal average integrated quantum flux density (Qint) varied 25-fold between the canopy top and the canopy bottom. Cladode cross-sectional shape was unaffected by irradiance, but cladode dry mass per unit total area (MA) varied 2-fold within the canopy light gradient. This resulted primarily from light-dependent changes in cladode thickness (volume to total area ratio,V / AT) and to a lesser extent from changes in cladode density (D, MA = DV / AT). Nitrogen content, and the volume of mesophyll per unit surface area increased with increasing Qint and V / AT, resulting in positive scaling of foliage photosynthetic potential (capacity of photosynthetic electron transport and maximum Rubisco carboxylase activity per unit area) with light. However, nitrogen content per unit dry mass and the volume fraction of mesophyll decreased with increasing irradiance. This was explained by greater fractional investment in mechanical tissues in cladodes with greater volume to surface area ratio. This trade-off between photosynthetic and support investments reduced the cladode photosynthetic plasticity. Our study demonstrates a significant acclimation potential of species with cylindrical foliage that should be included in larger-scale carbon balance estimations of arid and saline communities.
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Gran, M., J. Carrera, S. Olivella y M. W. Saaltink. "Modeling evaporation processes in a saline soil from saturation to oven dry conditions". Hydrology and Earth System Sciences Discussions 8, n.º 1 (18 de enero de 2011): 529–54. http://dx.doi.org/10.5194/hessd-8-529-2011.
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Abstract. Thermal, suction and osmotic gradients interact during evaporation from a salty soil. Vapor fluxes become the main water flow mechanism under very dry conditions. A coupled nonisothermal multiphase flow and a reactive transport model of a salty sand soil was developed to study such an intricate system. The model was calibrated with data from an evaporation experiment (volumetric water content, temperature and concentration). The retention curve and relative permeability functions were modified to simulate oven dry conditions. Experimental observations were satisfactorily reproduced, which suggests that the model can be used to assess the underlying processes. Results show that evaporation is controlled by heat, and limited by salinity and liquid and vapor fluxes. Below evaporation front vapor flows downwards controlled by temperature gradient and thus generates a dilution. Vapor diffusion and dilution are strongly influenced by heat boundary conditions. Gas diffusion plays a major role in the magnitude of vapor fluxes.
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Maheswaran, P. A., S. Satheesh Kumar y T. Pradeep Kumar. "Intra annual Variability of the Arabian Sea high salinity water mass in the South Eastern Arabian Sea during 2016 17". Defence Science Journal 69, n.º 2 (6 de marzo de 2019): 149–55. http://dx.doi.org/10.14429/dsj.69.14217.
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Intra-annual variability of the Arabian Sea high salinity water mass (ASHSW) in the South Eastern Arabian Sea (SEAS) and Gulf of Mannar (GoM) are addressed in this paper by utilisng the monthly missions carried out onboard INS Sagardhwani during 2016-17. Our observations revealed that the ASHSW was evident along the SEAS irrespective of seasons, whereas in the GoM the presence of ASHSW was observed during winter. The processes such as downwelling/up-welling, coastal currents, intrusion of low saline waters, stratification are clearly affects the spreading of the ASHSW. The characteristics such as core salinity value, depth and thickness of ASHSW exhibited remarkable spatio-temporal variability. Lateral mixing with the low saline waters in the region during winter reduces its core salinity. The intrusion of low saline waters was clearly seen upto 15 ON but the intrusion of low saline waters is not flowing through the GoM. The interface between the ASHSW and the prevailing low saline waters showed strong horizontal gradients of salinity. The presence of the ASHSW makes difference in the SLD and the below layer gradient which is sufficient to complicate or influence sound transmission. The spatio temporal variability of the ASHSW and its acoustic relevance are documented in this paper.
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Sánchez, G. y F. Méndez. "Power generation cell driven by osmotic pressure in microchannels with hydrophobic surfaces and viscoelectric effects". Journal of Physics D: Applied Physics 55, n.º 25 (1 de abril de 2022): 255501. http://dx.doi.org/10.1088/1361-6463/ac5ef1.
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Abstract A theoretical study that explores power generation via streaming potential and osmotic gradients is proposed. The system is compounded by an osmotic membrane that has different saline concentrations on each side. This concentration gradient promotes a volumetric flux rate inside a microchannel with parallel plates whose surfaces are made of modified hydrophobic fumed silica, thus, the no-slip condition is no longer sustained. Aside from these characteristics, we consider viscoelectric effects in the analysis. The set of equations is written in dimensionless variables, which are solved with integrodifferential methods, permitting us to obtain semi-analytical solutions for velocity, pressure fields, and the most important: the electric potential generated for the system. This setup converts concentration gradients into electric energy in the form of streaming potential. Besides, we demonstrate that hydrophobic surfaces promote a greater induced streaming potential, nonetheless, for high potentials appears a saturation phenomenon which avoids the growth of the induced electric potential no matter how large the slip-conditions could be.
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Arenson, Lukas U. y Dave C. Sego. "The effect of salinity on the freezing of coarse-grained sands". Canadian Geotechnical Journal 43, n.º 3 (1 de marzo de 2006): 325–37. http://dx.doi.org/10.1139/t06-006.
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Unfrozen water is very important because it has a significant influence on the mechanical response of a frozen soil. It is particularly important to know if the water is available as free water or if it is bonded to the solid particles. A simple experimental setup was used to observe the freezing process of a coarse-grained soil under controlled freezing gradients and salinities. A fluorescent tracer helped to determine the location of the unfrozen water during freezing. Depending on the salinity and the thermal gradient, pockets of unfrozen water with a much higher salt concentration were trapped in pores under increased pore pressures. Even at salinities as low as 2 g/L, spicular ice crystals were identified with channels containing unfrozen water between the ice crystals. The experiments further indicate that the unfrozen water in coarse-grained frozen soils is in the middle of the pore space compared to the unfrozen water film that immediately surrounds fine-grained saline or non-saline soil particles.Key words: frozen soil, salinity, frost penetration, thermal conductivity.
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Burwash, I. G., A. D. Forbes, M. Sadahiro, E. D. Verrier, A. S. Pearlman, R. Thomas, C. Kraft y C. M. Otto. "Echocardiographic volume flow and stenosis severity measures with changing flow rate in aortic stenosis". American Journal of Physiology-Heart and Circulatory Physiology 265, n.º 5 (1 de noviembre de 1993): H1734—H1743. http://dx.doi.org/10.1152/ajpheart.1993.265.5.h1734.
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The anatomy of degenerative valvular aortic stenosis has been poorly represented in animal models, limiting the evaluation of noninvasive echo-Doppler measures of transvalvular volume flow rate and stenosis severity during progressive disease evolution or under conditions of changing volume flow rates. To study these issues, chronic valvular aortic stenosis, characterized by stiff leaflets without commissural fusion, was created in nine adult mongrel dogs by suturing pericardial covered Teflon-felt pads into the sinuses of Valsalva below the coronary ostia during hypothermic cardiac arrest. In the eight surviving dogs, echo-Doppler examinations were performed weekly for up to 8 wk postoperatively. Simultaneous invasive micromanometer pressure data were collected at 2-wk intervals in all subjects, with simultaneous ascending aortic transit time-volume flow measurement in four subjects. Volume flow rates were altered with saline and dobutamine infusions during invasive studies for comparison of echo-Doppler and invasive pressure gradients, volume flow, and valve areas. Serial echo-Doppler follow-up (39 +/- 11 days) demonstrated that, from baseline to final study, mean transvalvular pressure gradient increased (4 +/- 1 to 38 +/- 7 mmHg, P = 0.001), continuity equation aortic valve area decreased (2.06 +/- 0.18 to 0.54 +/- 0.04 cm2, P < 0.0001), and progressive left ventricular hypertrophy developed (62 +/- 6 to 114 +/- 9 g, P = 0.0003). Echo-Doppler and invasive data correlated well for measures of transvalvular pressure gradients (n = 98, maximum instantaneous gradient r = 0.95, mean gradient r = 0.91), volume flow (n = 75, stroke volume r = 0.86, cardiac output r = 0.86), and valve area (n = 73, r = 0.73) despite acute alterations in volume flow and progressive disease evolution. This chronic canine model, with anatomy and hemodynamics similar to clinical degenerative valvular aortic stenosis, should provide a valuable tool for investigating clinically relevant new measures of stenosis severity with use of invasive or noninvasive techniques.
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Wang, Y., G. J. Heigenhauser y C. M. Wood. "Ammonia movement and distribution after exercise across white muscle cell membranes in rainbow trout". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 271, n.º 3 (1 de septiembre de 1996): R738—R750. http://dx.doi.org/10.1152/ajpregu.1996.271.3.r738.
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Manipulations of pH and electrical gradients in a perfused preparation were used to analyze the factors controlling ammonia distribution and flux in trout white muscle after exercise. Trout were exercised to exhaustion, and then an isolated-perfused white muscle preparation with discrete arterial inflow and venous outflow was made from the posterior portion of the tail. The tail-trunks were perfused with low (7.4)-, medium (7.9)-, and high (8.4)-pH saline, achieved by varying HCO3- concentration ([HCO3-]) at constant Pco2. Intracellular and extracellular pH, ammonia, CO2, K+, Na+, and Cl- were measured. Muscle intracellular pH was not affected by changes in extracellular pH. Increasing extracellular pH caused a decrease in the transmembrane NH3 partial pressure (PNH3) gradient and a decrease in ammonia efflux. When extracellular K+ concentration was increased from 3.5 to 15 mM in the medium-pH group, a depolarization of the muscle cell membrane potential from -92 to -60 mV and a 0.1-unit depression in intracellular pH occurred. Ammonia efflux increased despite a marked reduction in the PNH3 gradient. Amiloride (10(-4) M) had no effect, indicating that Na+/H(+)-NH4+ exchange does not participate in ammonia transport in this system. A comparison of observed intracellular-to-extracellular ammonia distribution ratios with those modeled according to either pH or Nernst potential distributions supports a model in which ammonia distribution across white muscle cell membranes is affected by both pH and electrical gradients, indicating that the membranes are permeable to both NH3 and NH4+. Membrane potential, acting to retain high levels of NH4+ in the intracellular compartment, appears to have the dominant influence during the postexercise period. However, at rest, the pH gradient may be more important, resulting in much lower intracellular ammonia levels and distribution ratios. We speculate that the muscle cell membrane NH3-to-NH4+ permeability ratio in trout may change between the rest and postexercise condition.
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Karagianni, Aikaterini, Georgia Stamou, Matina Katsiapi, Polina Polykarpou, Gerald Dörflinger y Evangelia Michaloudi. "Zooplankton communities in Mediterranean temporary lakes: the case of saline lakes in Cyprus". Annales de Limnologie - International Journal of Limnology 54 (2018): 14. http://dx.doi.org/10.1051/limn/2018007.
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Temporary saline lakes are diverse ecosystems mostly located in arid areas. In the Mediterranean region they are among the most remarkable, but also the most threatened habitats; thus, effective management and conservation plans need to consider their special hydrological and ecological features and requirements. They are mainly fishless systems and so zooplankton is the driver of the trophic cascade. Our aim was to determine zooplankton communities' composition and biomass in seven temporary saline lakes of Cyprus and investigate their relation with environmental variables. Salinity ranged between <2 and 300 ppt and was a key factor shaping zooplankton community. In hyposaline conditions zooplankton communities exhibited higher species diversity than in meso- and hypersaline conditions. Hyposaline lakes were dominated by Arctodiaptomus salinus (Daday, 1885), Daphnia magna Straus, 1820 and Moina brachiata (Jurine, 1820) in terms of biomass, while meso- and hypersaline lakes by anostracans Artemia salina (Linnaeus, 1758) and Phallocryptus spinosus (Milne-Edwards, 1840) or M. brachiata and D. magna highlighting competition as another factor shaping the zooplankton community. We conclude that zooplankton reflects environmental pressures, such as salinity fluctuations which are closely related to water level fluctuations, in the mostly fishless Mediterranean temporary saline lakes. Moreover, salinity fluctuations should be considered a key factor for typological considerations in quality assessments, restoration and management plans in temporary saline systems since it can reflect the hydrological variations on the communities across different years and seasons by salinity gradient even for the same water body.
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Loring, S. H., K. Yoshino, W. R. Kimball y G. M. Barnas. "Gravitational and shear-associated pressure gradients in the abdomen". Journal of Applied Physiology 77, n.º 3 (1 de septiembre de 1994): 1375–82. http://dx.doi.org/10.1152/jappl.1994.77.3.1375.
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The abdomen has been variously characterized as a hydrostatic system, in which pressures exhibit a gravitational gradient and pressure fluctuations are spatially uniform, and as a compartment, in which pressure gradients are not simply gravitational and pressure fluctuations differ markedly from place to place. To characterize the pressures acting on the ventral abdominal wall, we used saline-filled catheters and air-filled balloons in anesthetized dogs in various body positions during spontaneous breathing and mechanical ventilation. Pressures were measured in the stomach and at multiple sites next to the abdominal wall. Under most circumstances, measurements next to the abdominal wall exhibited a hydrostatic gravitational gradient of approximately 0.89 cmH2O/cm height and pressure fluctuations were spatially homogeneous. Deviations from this hydrostatic behavior were seen when abdominal pressures were compared with gastric pressures, when measurements were made with a balloon catheter, and when the lower abdomen was constricted with a binder. Analysis of these and previously published data suggests that the abdomen does, at times, behave like a hydraulic system but can deviate from simple hydrostatic behavior to the extent that shape-stable abdominal viscera are deformed.
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Coelho, Paulo Marcos Z., Arnon D. Jurberg, Áureo A. Oliveira y Naftale Katz. "Use of a saline gradient for the diagnosis of schistosomiasis". Memórias do Instituto Oswaldo Cruz 104, n.º 5 (agosto de 2009): 720–23. http://dx.doi.org/10.1590/s0074-02762009000500010.
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He, Baozhong, Jianli Ding, Wenjiang Huang y Xu Ma. "Spatiotemporal Variation and Future Predictions of Soil Salinization in the Werigan–Kuqa River Delta Oasis of China". Sustainability 15, n.º 18 (21 de septiembre de 2023): 13996. http://dx.doi.org/10.3390/su151813996.
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Soil salinization is a serious global issue; by 2050, without intervention, 50% of the cultivated land area will be affected by salinization. Therefore, estimating and predicting future soil salinity is crucial for preventing soil salinization and investigating potential arable land resources. In this study, several machine learning methods (random forest (RF), Light Gradient Boosting Machine (LightGBM), Gradient Boosting Decision Tree (GBDT), and eXtreme Gradient Boosting (XGBoost)) were used to estimate the soil salinity in the Werigan–Kuqa River Delta Oasis region of China from 2001 to 2021. The cellular automata (CA)–Markov model was used to predict soil salinity types from 2020 to 2050. The LightGBM method exhibited the highest accuracy, and the overall prediction accuracy of the methods had the following order: LightGBM > RF > GBRT > XGBoost. Moderately saline, severely saline, and saline soils were dominant in the east and south of the research area, while non-saline and mildly saline soils were widely distributed in the inner oasis area. A marked decreasing trend in the soil salt content was observed from 2001 to 2021, with a decreasing rate of 4.28 g/kg·10 a−1. The primary change included the conversion of mildly and severely saline soil types to non-saline soil. The generalized difference vegetation index (51%), Bio (30%), and temperature vegetation drought index (27%) had the greatest influence, followed by variables associated with soil attributes (soil organic carbon and soil organic carbon stock) and terrain (topographic wetness index, slope, aspect, curvature, and topographic relief index). Overall, the CA–Markov simulation resulted exhibited suitable accuracy (kappa = 0.6736). Furthermore, areas with non-saline and mildly saline soils will increase while areas with other salinity levels will continue to decrease from 2020 to 2050. From 2046 to 2050, numerous areas with saline soil will be converted to non-saline soil. These results can provide support for salinization control, agricultural production, and soil investigations in the future. The gradual decline in soil salinization in the research area in the past 20 years may have resulted from large-scale land reclamation, which has turned saline alkali land into arable land and is also related to effective measures taken by the local government to control salinization.
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Blinn, Dean W. "Diatom Community Structure Along Physicochemical Gradients in Saline Lakes". Ecology 74, n.º 4 (junio de 1993): 1246–63. http://dx.doi.org/10.2307/1940494.
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Krell, W. S. y J. R. Rodarte. "Effects of acute pleural effusion on respiratory system mechanics in dogs". Journal of Applied Physiology 59, n.º 5 (1 de noviembre de 1985): 1458–63. http://dx.doi.org/10.1152/jappl.1985.59.5.1458.
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We determined regional (Vr) and overall lung volumes in six head-up anesthetized dogs before and after the stepwise introduction of saline into the right pleural space. Functional residual capacity (FRC), as determined by He dilution, and total lung capacity (TLC) decreased by one-third and chest wall volume increased by two-thirds the saline volume added. Pressure-volume curves showed an apparent increase in lung elastic recoil and a decrease in chest wall elastic recoil with added saline, but the validity of esophageal pressure measurements in these head-up dogs is questionable. Vr was determined from the positions of intraparenchymal markers. Lower lobe TLC and FRC decreased with added saline. The decrease in upper lobe volume was less than that of lower lobe volume at FRC and was minimal at TLC. Saline increased the normal Vr gradient at FRC and created a gradient at TLC. During deflation from TLC to FRC before saline was added, the decrease in lung volume was accompanied by a shape change of the lung, with greatest distortion in the transverse (ribs to mediastinum) direction. After saline additions, deflation was associated with deformation of the lung in the cephalocaudal and transverse directions. The deformation with saline may be a result of upward displacement of the lungs into a smaller cross-sectional area of the thoracic cavity.
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Medeiros, Carlinda Raílly, Franciely Ferreira Paiva, Raphael Ligeiro, Joseline Molozzi y Adriano Sanches Melo. "Saline gradient drives functional nestedness of polychaete communities in tropical estuaries". Estuarine, Coastal and Shelf Science 251 (abril de 2021): 107185. http://dx.doi.org/10.1016/j.ecss.2021.107185.
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Pilati, Alberto, Andrea E. Biasotti y Giuliana A. Montelpare. "Corta meromixis en un lago somero de la región semiárida pampeana". Biología Acuática, n.º 41 - en curso (16 de febrero de 2024): 037. http://dx.doi.org/10.24215/16684869e037.
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Los lagos meromícticos son aquellos que no se mezclan en su totalidad debido a un fuerte gradiente salino que separa el mixolimnion (superficial, menos salino) del monimolimnion (profundo, más salino). La laguna Este de la Reserva Provincial Parque Luro (La Pampa) es una típica laguna hipersalina (salitral) que luego de una lluvia excepcional mostró una corta meromixis. El objetivo del presente trabajo fue determinar los cambios en las características físico-químicas y en las comunidades planctónicas durante la meromixis, la cual duró al menos 7 meses. En comparación con el monimolimnion, el mixolimnion se caracterizó por tener menor salinidad y nutrientes; sin embargo, tuvo mayor pH, oxígeno disuelto, clorofila, y sólidos orgánicos. La escasa profundidad de esta laguna y la acción de los vientos ocasionaron el fin de la meromixis. El fitoplancton estuvo dominado casi exclusivamente por Dunaliella salina y durante la meromixis no se observaron diferencias en la densidad o en la biomasa en su distribución vertical. El zooplancton (generalmente dominado por Artemia persimilis) redujo su riqueza con el aumento de salinidad. Mientras duró la meromixis, esta especie coexistió con Boeckella poopoensis, y ambas presentaron altas densidades de juveniles en el mixolimnion respecto del monimolimnion. El episodio de una corta meromixis, como el descripto en este estudio, permitió observar diversas condiciones limnológicas y el desarrollo de un mayor número de especies de zooplancton, algunas de ellas endémicas de la región. Estos atributos, transforman a este lago somero en un sitio de particular interés para su conservación.
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Satria Anugerah Suhendra, Muthia Elma, Isna Syauqiyah, Dwi Resa Lamandau, Siti Fatimah y Aulia Rahma. "Energy from Salinity Gradient of Wetland Saline Water Using Reverse Electrodialysis Membrane". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 101, n.º 2 (20 de enero de 2023): 46–59. http://dx.doi.org/10.37934/arfmts.101.2.4659.
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Reverse electrodialysis (RED) membrane is an emerging renewable energy which harvest electricity from mixing two streams on different salinities. In real practice is still not clearly defined for the effectiveness of salinity gradient power (SGP)-RED due to the limitation of artificial saline water. Generally, South Kalimantan Indonesia is rich by wetland and coastal area. Due to that wetland saline water is potential as saline water sources for collection the SGP. This experiment aims to investigate the impact of natural feed stream wetland saline water was collected from Muara Halayung South Kalimantan-Indonesia to demineralized (WSW),artificial brackish (ABW) (0.35 wt %NaCl), and artificial seawater (ASW) (3.5 wt % NaCl) in terms of power density measured on a lab-scale RED membrane stack prototype 12 x 12 cm. Ion exchange membrane (IEM) was used in this work consisted from cellulose modified Anion Exchange Membrane (AEM) by EDTA-quaternization (EDC) process. Whereas, Cation Exchange Membrane (CEM) was employing Nafion NR-212 with thickness 0.002 in. Lab-scale RED tests operated 3 hours into area system has 121cm2; AEM and CEM area have 100cm2; uses spacer nylon a pair between membranes; and two electrodes by stainless-steal and copper. Feed water was into RED system then measured power density as an electrical energy potential that from separate ions by AEM and CEM. The result among of this experiment, characteristic of wetland saline water naturally had electro conductivity (EC) 135.6 µS/cm; TOM 15.2 ppm; and has ionic compound higher in Na+ and Cl- which is Cl- compound as one of potentially formed salinity on that wetland water and become potential uses one of natural feed water in RED system. The highest energy power density on RED process obtained by mixed WSW:ASW was 1.43 W/m2. While ratio of the gradient salinity WSW:ABW to ABW:ASW were increasing 86% which has 1:5 to 1:30 as the effect of stream mixing by two natural feed water.
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Fagerland, Jenny, Anna Finne-Wistrand y Daniela Pappalardo. "Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of rac-β-butyrolactone with lactide". New Journal of Chemistry 40, n.º 9 (2016): 7671–79. http://dx.doi.org/10.1039/c6nj00298f.
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Colombetti, G., R. Bräucker y H. Machemer. "Photobehaviour of Fabrea salina: Responses to directional and diffused gradient-type illumination". Journal of Photochemistry and Photobiology B: Biology 15, n.º 3 (agosto de 1992): 253–57. http://dx.doi.org/10.1016/1011-1344(92)85129-i.
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Burchill, C. A. y N. C. Kenkel. "Vegetation–environment relationships of an inland boreal salt pan". Canadian Journal of Botany 69, n.º 4 (1 de abril de 1991): 722–32. http://dx.doi.org/10.1139/b91-098.
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Vegetation composition and community structure of boreal inland salt pans near the shore of Dawson Bay, Lake Winnipegosis, Manitoba, were examined. Eight vegetation associations and eight species groups were described from the site. Most of the vegetation associations were dominated by a single graminoid or graminoid-like species. Species composition in the most saline areas was similar to that of prairie salt pans to the south, whereas the vegetation of less saline areas showed affinities to both prairie and boreal forest. Examination of vegetation–environment relationships indicated that soil salinity was the moost important factor determining vegetation pattern. Other soil factors such as nutient levels, bulk density, and percent organic matter were of secondary importance. Species richness increased with decreasing salinity, but trends in Shannon–Weaver diversity and evenness along the salinity gradient were more complex. Despite the salinity gradient being environmentally continuous, strong vegetational discontinuities were noted. It is suggested that these discontinuities arose through interspecific competitive interaction and displacement mediated by differences in the salt tolerance of species. Key words: competition, discontinuity, gradient, halophyte, plant community, salinity.
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Gao, Chun Juan, Qi Zhang, Ze Liang Dong, Shu Yuan Guo y Xi Ping Huang. "Study of Establishment and Operation of Salt-Gradient Solar Pond". Applied Mechanics and Materials 472 (enero de 2014): 409–12. http://dx.doi.org/10.4028/www.scientific.net/amm.472.409.
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In this paper, it was presented that the establishment and experimental investigation of a salt-gradient solar pond. The solar pond was filled with salty water to form three zones (e.g., upper convective zone, non-convective zone and lower convective zone) accordingly with different methods of saline injection. Parameters like salinity and temperature were measured and recorded daily at various locations in the salt-gradient solar pond. The results showed that solar pond collected and stored solar energy for a long period of time can be possible by controlling the thickness and salinity of salt gradient layer of the solar pond.
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Shao, Xiaoxiao, Yu Hou y Xin Zhong. "Intense jet flow with symmetric vortices induced by saline concentration gradient at free surface of a drying saline droplet". International Communications in Heat and Mass Transfer 128 (noviembre de 2021): 105573. http://dx.doi.org/10.1016/j.icheatmasstransfer.2021.105573.
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Bajona, Pietro, Stefano Salizzoni, Stijn Vandenberghe, Charles J. Bruce, Giovanni Speziali y Kenton J. Zehr. "“The Balloon Plug Concept” for Tricuspid Valve Repair Ex Vivo Proof of Concept". Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 10, n.º 1 (enero de 2015): 27–32. http://dx.doi.org/10.1097/imi.0000000000000124.
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Objective Functional tricuspid regurgitation (TR) is recognized as a significant cause of morbidity and mortality in cardiothoracic surgery. We hypothesized that a variably expandable, transvalvular balloon mounted on a catheter could be percutaneously inserted and fixed to the right ventricle apex. This novel approach could provide a minimally invasive way to eliminate clinically relevant TR caused by annular dilatation. This study was performed to test the ex vivo hemodynamic effects and the feasibility of the “balloon plug concept.” Methods Twenty harvested calf tricuspid valves were placed in a mechanical simulator. Tricuspid regurgitation was created by annular stretching and displacement of the papillary muscles so as to create central TR. A flexible catheter with a 4-cm–long, soft, fusiform balloon was positioned across the valve so that the balloon was suspended centrally across the valve annular plane. After activating the mechanical ventricle, data were collected with balloon inflation volumes of saline from 5 to 20 mL. Transvalvular pressure gradients and leaflet mechanics were evaluated with incremental inflation. Results In all cases, 5-mL inflation did not significantly reduce TR and 20-mL inflation caused obstruction to antegrade flow (mean transvalvular gradient > 4 mm Hg). Inflation between 10 and 15 mL caused significant reduction in TR with acceptable transvalvular gradients (<3 mm Hg). Conclusions The balloon plug concept showed promising ex vivo hemodynamic results. In vivo investigations are warranted to evaluate percutaneous techniques, thrombogenicity, and effects of repeated balloon-leaflet contact on valve integrity.
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Mayo, Alan L., David G. Tingey, Kevin A. Rey, Tony D. Winkel, John H. McBride, Stephen T. Nelson, Gregory T. Carling, Jiri Bruthans y Erik C. Petersen. "Shallow groundwater flow and inverted fresh/saline-water interface in a hypersaline endorheic basin (Great Basin, USA)". Hydrogeology Journal 28, n.º 8 (12 de agosto de 2020): 2877–902. http://dx.doi.org/10.1007/s10040-020-02209-8.
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AbstractPilot Valley is an 828-km2 arid-region endorheic basin in western USA. Bounding mountain ranges rise as much as 1,900 m above the nearly flat 379-km2 playa floor. Up to 3.8 m of Pleistocene Lake Bonneville mud and thin oolitic sand layers form the surface layer of the basin floor. Groundwater conditions were evaluated using data from shallow monitoring wells and borings, springs, infiltrometer measurements, slug and dilution tests, geophysical transects, and precision elevation surveys. Alluvial fan groundwater discharges at fan/playa interface springs and underflows to the shallow basin sediments along the western side of the basin; the groundwater only underflows along the eastern side. Precision surveying established a Lake Bonneville shore-line break in slope as the cause of the spring discharges. Tectonic tilting causes groundwater to flow from east to west and to the topographic low. Monthly measured and pressure transducer data established seasonal pressure responses and upward groundwater gradients. All basin groundwater is lost to evapotranspiration at the topographic low, where a thin salt pan has developed. Groundwater evolves from fresh to hypersaline near the alluvial fan/playa interface where there is an inverted salinity gradient and a groundwater pressure ridge. The pressure ridge and inverted salinity interface are due to: (1) osmotic pressure established between the oolitic sand of high hydraulic conductivity and the overlying low-hydraulic-conductivity lake mud at the fan/playa interface, and (2) the collision between fresh groundwater flow driven by a steep hydraulic head and hypersaline groundwater flow driven by a nearly flat hydraulic head.
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Costa, Raiane S., Joseline Molozzi, Luiz U. Hepp, Renato M. Rocha y José E. L. Barbosa. "Diversity partitioning of a phytoplankton community in semiarid salterns". Marine and Freshwater Research 67, n.º 2 (2016): 238. http://dx.doi.org/10.1071/mf14210.
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Salterns consist of a series of interconnected evaporators that form sectors in the salterns. Their operation generates an increasing saline gradient, which influences species diversity. The present study was conducted in three salterns, with the goal of evaluating the diversity partitioning of phytoplankton along the saline gradient. We identified 65 taxa; the species richness was similar among the salterns, with higher values occurring in initial sectors and a downward trend with increasing salinity. In the partitioning analysis, the α diversity contributed 33.8% of the total diversity. The diversity variance showed a strong reduction from the α to β1 (33.8–6.3%). At higher scales, the highest species richness was found between salt marshes; however, there was lower diversity and a decrease in similarity from the lower to the higher scale. Therefore, we demonstrated that the greater variance in phytoplankton richness was at higher scales.
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Roberts, D., A. McMinn, N. Johnston, D. B. Gore, M. Melles y H. Cremer. "An analysis of the limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica". Antarctic Science 13, n.º 4 (diciembre de 2001): 410–19. http://dx.doi.org/10.1017/s0954102001000578.
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The limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica, is presented. Saline lakes, saline ponds and freshwater ponds are represented in this dataset. The Windmill Island lake diatom flora represents an intermediate floral assemblage between that of the freshwater lakes of the Larsemann Hills and the saline lakes of Vestfold Hills, East Antarctica. Variations within this assemblage are related to water chemistry variables in the Windmill Island lakes. In particular, a lakewater salinity/phosphate gradient can explain the variation observed in the sedimentary diatom flora of the lakes and ponds included in this study.
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Henry, R. P., Y. Wang y C. M. Wood. "Carbonic anhydrase facilitates CO2 and NH3 transport across the sarcolemma of trout white muscle". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 272, n.º 6 (1 de junio de 1997): R1754—R1761. http://dx.doi.org/10.1152/ajpregu.1997.272.6.r1754.
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An isolated, perfused tail preparation was used to study the role of carbonic anhydrase (CA) in CO2 and NH3 transport across the sarcolemma of white muscle in the rainbow trout. Tissue was perfused with either control saline or saline containing the CA inhibitors quaternary ammonium sulfanilamide (QAS) or acetazolamide (Az). Inhibition of extracellular CA by QAS reduced CO2 efflux by approximately 30% and caused a significant increase in intracellular PCO2. Inhibition of total muscle CA activity (extracellular and intracellular) by Az also caused a reduction in CO2 efflux, but selective inhibition of intracellular CA only had no effect. Inhibition of both extracellular and intracellular CA activity resulted in increases in total intracellular ammonia concentrations, intracellular NH3 partial pressure (PNH3) and an increased PNH3 gradient across the sarcolemma. This suggests that both extracellular and intracellular CA function in normal NH3 transport out of the muscle. We suggest that CA in the extracellular boundary layer facilitates CO2 transport via the catalyzed hydration of CO2, thus maintaining the PCO2 gradient across the sarcolemma. H ions produced by that reaction serve to protonate excreted NH3, which helps maintain the PNH3 gradient. Thus CO2 and NH3 excretion are linked by the action of CA.
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Silva, Wasana de y Mala Amarasinghe. "Response of mangrove plant species to a saline gradient: Implications for ecological restoration". Acta Botanica Brasilica 35, n.º 1 (marzo de 2021): 151–60. http://dx.doi.org/10.1590/0102-33062020abb0170.
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Sajo-Castelli, A. M., M. A. Fortes y M. Raydan. "Preconditioned conjugate gradient method for finding minimal energy surfaces on Powell–Sabin triangulations". Journal of Computational and Applied Mathematics 268 (octubre de 2014): 34–55. http://dx.doi.org/10.1016/j.cam.2014.02.030.
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Wang, Xinxin, Zhen Han, Zhihui Bai, Jingchun Tang, Anzhou Ma, Jizheng He y Guoqiang Zhuang. "Archaeal community structure along a gradient of petroleum contamination in saline-alkali soil". Journal of Environmental Sciences 23, n.º 11 (noviembre de 2011): 1858–64. http://dx.doi.org/10.1016/s1001-0742(10)60640-7.
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Shao, Lele, Yi Liu, Xiaojing Tian, Huicong Wang, Qianqian Yu, Xingmin Li y Ruitong Dai. "Inactivation of Staphylococcus aureus in phosphate buffered saline and physiological saline using ohmic heating with different voltage gradient and frequency". Journal of Food Engineering 274 (junio de 2020): 109834. http://dx.doi.org/10.1016/j.jfoodeng.2019.109834.
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Liang, Xiaolong, Xiaoyu Wang, Ning Zhang y Bingxue Li. "Biogeographical Patterns and Assembly of Bacterial Communities in Saline Soils of Northeast China". Microorganisms 10, n.º 9 (5 de septiembre de 2022): 1787. http://dx.doi.org/10.3390/microorganisms10091787.
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Increasing salinity undermines soil fertility and imposes great threats to soil ecosystem productivity and ecological sustainability. Microbes with the ability to adapt to environmental adversity have gained increasing attention for maintenance and restoration of the salt-affected soil ecosystem structure and functioning; however, the characterization of microbial communities in saline–sodic soils remains limited. This study characterized the bacterial community composition and diversity in saline–sodic soils along a latitude gradient across Northeast China, aiming to reveal the mechanism of physicochemical and geographic characteristics shaping the soil bacterial communities. Our results showed that the bacterial community composition and diversity were significantly impacted by soil pH, electrical conductivity, Na+, K+, Cl−, and CO32−. Significant differences in bacterial diversity were revealed along the latitude gradient, and the soil factors accounted for 58.58% of the total variations in bacterial community composition. Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, and Bacteroidetes were dominant across all samples. Actinobacteria and Gemmatimonadetes were significantly enriched in high soil sodicity and salinity, while Acidobacteria and Proteobacteria were suppressed by high pH and salt stress in the saline–sodic soils. Increase in soil pH and salinity significantly decreased bacterial species richness and diversity. Community composition analysis indicated that bacterial taxonomic groups (e.g., Bacillus, Egicoccus, Truepera, Halomonas, and Nitrolancea) that may adapt well to high salinity were greatly enriched in the examined soils. The findings collectively evidenced that bacterial community composition and diversity in a broad biographic scale were determined by niche-based environmental characteristics and biotic interactions. The profiling of the soil bacterial communities along the latitude gradient will also provide a basis for a better understanding of the salt-affected soil ecosystem functioning and restoration of these soil ecosystems.
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Storesund, Julia E., Anders Lanzèn, Eva-Lena Nordmann, Hilde Rief Armo, Olga Maria Lage y Lise Øvreås. "Planctomycetes as a Vital Constituent of the Microbial Communities Inhabiting Different Layers of the Meromictic Lake Sælenvannet (Norway)". Microorganisms 8, n.º 8 (29 de julio de 2020): 1150. http://dx.doi.org/10.3390/microorganisms8081150.
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Meromictic lakes are permanently stratified lakes that display steep gradients in salinity, oxygen and sulphur compounds tightly linked to bacterial community structure and diversity. Lake Sælenvannet is a meromictic lake located south of Bergen, Norway. The 26 m deep lake is connected to the open sea and permanently stratified into two layers separated by a chemocline. The upper water layer is brackish with major input from water runoff from the surroundings. The bottom layer consists of old saline water with low or no oxygen concentrations. Bacteria from phylum Planctomycetes are reported to be ubiquitous in lake environments. They are involved in the degradation of complex carbon sources in aquatic environments and are also linked to anaerobic processes such as fermentation and sulphur reduction. To study Planctomycete distribution along a chemical gradient, we sampled the water column throughout Lake Sælenvannet in 2012 and profiled the microbial community using 16S rRNA amplicon sequencing (metabarcoding) with 454 pyrosequencing. Planctomycetes related 16S rRNA gene sequences were found to be present both in the oxic and anoxic parts of the lake and showed an uneven distribution throughout the water column, with the highest relative abundance of 10% found in the saline anoxic layer at 15 m depth. In a follow-up study in 2014, samples from eight different depths were collected for enrichment and isolation of novel Planctomycetes. This study resulted in successful isolation in pure culture of 10 isolates affiliated to four different genera from the family Planctomycetaceae. One strain closely related to Blastopirellula cremea was isolated from 9 m depth, and two novel strains affiliated to the genera Stieleria and Gimesia were isolated at 7 and 9 m depths, respectively. Furthermore, seven isolates with identical 16S rRNA gene sequences were retrieved from seven different depths which varied greatly in salinity and chemical composition. These isolates likely represent a new species affiliated to Rubinisphaera. The adaptation of this novel Planctomycete to water depths spanning the entire chemical gradient could indicate a high phenotypic plasticity and/or a very efficient survival strategy. Overall, our results show the presence of a diverse group of Planctomycetes in Lake Sælenvannet, with a strong potential for novel adaptations to chemical stress factors.
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Kimura, Satoshi, William Smyth y Eric Kunze. "Turbulence in a Sheared, Salt-Fingering-Favorable Environment: Anisotropy and Effective Diffusivities". Journal of Physical Oceanography 41, n.º 6 (1 de junio de 2011): 1144–59. http://dx.doi.org/10.1175/2011jpo4543.1.
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Abstract Direct numerical simulations (DNS) of a shear layer with salt-fingering-favorable stratification have been performed for different Richardson numbers Ri and density ratios Rρ. In the absence of shear (Ri = ∞), the primary instability is square planform salt fingering, alternating cells of rising and sinking fluid. In the presence of shear, salt fingering takes the form of salt sheets, planar regions of rising and sinking fluid, aligned parallel to the sheared flow. After the onset of secondary instability, the flow becomes turbulent. The continued influence of the primary instability distorts the late-stage structure and hence biases isotropic estimates of the turbulent kinetic energy dissipation rate ε. In contrast, thermal and saline gradients evolve to become more isotropic than velocity gradients at their dissipation scales. Thus, the standard observational methodology of estimating the turbulent kinetic energy dissipation rate ε from vertical profiles of microscale gradients and assuming isotropy can underestimate its true value by a factor of 2–3, whereas estimates of thermal and saline dissipation rates using this approach are relatively accurate. Likewise, estimates of Γ from vertical profiles overestimate the true Γ by roughly a factor of 2. Salt sheets are ineffective at transporting momentum. Thermal and saline effective diffusivities decrease with decreasing Ri, despite the added energy source provided by background shear. After the transition to turbulence, the thermal to saline flux ratio and the effective Schmidt number remain close to the values predicted by linear theory.
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Fahlevi, Mahfudz Reza. "Alternatif Pembuktian Hasil Kali Gradien Dua Garis Tegak Lurus Dalam Konteks Matematika Sekolah". Hexagon: Jurnal Ilmu dan Pendidikan Matematika 2, n.º 1 (13 de mayo de 2024): 30–48. http://dx.doi.org/10.33830/hexagon.v2i1.7594.
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Penelitian ini menyajikan ragam pembuktian konsep gradien garis, khususnya hasil kali gradien dua garis yang saling tegak lurus. Dalam matematika sekolah, konsep gradien cukup sering dijumpai. Namun, konsep tersebut jarang dilengkapi dengan penjelasan pembuktian yang akurat, sehingga dikhawatirkan menutup kesempatan siswa untuk berpikir kreatif dan berdampak buruk bagi budaya belajar matematika. Metode penelitian kualitatif digunakan melalui kajian kepustakaan yang bersumber dari video-video Youtube (Math&music, Indrajana, dan MaThCliX®), paparan pembuktian dalam situs diskusi ilmiah Quora (Sagar), serta pembuktian yang disusun oleh peneliti. Dengan mengompilasikan sumber-sumber yang ada, peneliti berupaya untuk menyajikan bukti matematis konsep hasil kali gradien dua garis yang saling tegak lurus. Materi yang dilibatkan dalam penelitian ini meliputi: (1) rotasi sederhana suatu garis, (2) konsep perbandingan dan kesebangunan, (3) teorema Pythagoras, (4) konsep tangen/tan dalam Trigonometri, serta (5) konsep perkalian dot dua vektor. Hasil penelitian menunjukkan bahwa konsep perkalian gradien dua garis tegak lurus dapat dibuktikan melalui beragam materi matematika sekolah, sehingga layak dijadikan referensi bagi guru ketika ingin menjelaskan konsep ini dengan baik dan benar serta memiliki dasar pembuktian yang kuat. Penelitian ini dapat berkembang lebih lanjut dengan melengkapi bukti hasil kali gradien dua garis tegak lurus menggunakan konsep lain yang relevan dalam materi matematika sekolah.
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Song, Tianran, Qiyun Liang, Zhaozhong Du, Xiaoqun Wang, Guanjun Chen, Zongjun Du y Dashuai Mu. "Salinity Gradient Controls Microbial Community Structure and Assembly in Coastal Solar Salterns". Genes 13, n.º 2 (21 de febrero de 2022): 385. http://dx.doi.org/10.3390/genes13020385.
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Salinity acts as a critical environmental filter on microbial communities in natural systems, negatively affecting microbial diversity. However, how salinity affects microbial community assembly remains unclear. This study used Wendeng multi-pond saltern as a model to evaluate the prokaryotic community composition and diversity and quantify the relative importance of ecological processes across salinity gradients. The results showed that low-saline salterns (45–80 g/L) exhibited higher bacterial diversity than high-saline salterns (175–265 g/L). The relative abundance of taxa assigned to Halomicrobiaceae, Rhodobacteraceae, Saprospiraceae, and Thiotrichaceae exhibited a hump-shaped dependence on increasing salinity. Salinity and pH were the primary environmental factors that directly or indirectly determined the composition and diversity of prokaryotic communities. Microbial co-occurrence network dynamics were more complex in the sediment than in the water of salterns. An infer Community Assembly Mechanisms by Phylogenetic-bin-based null model analysis (iCAMP) showed that microbial community assembly in sediment and water differed. Our findings provide more information about microbial community structure and the importance of various ecological processes in controlling microbial community diversity and succession along salinity gradients in water and sediment.
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Eiler, Alexander, Mona Johansson y Stefan Bertilsson. "Environmental Influences on Vibrio Populations in Northern Temperate and Boreal Coastal Waters (Baltic and Skagerrak Seas)". Applied and Environmental Microbiology 72, n.º 9 (septiembre de 2006): 6004–11. http://dx.doi.org/10.1128/aem.00917-06.
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ABSTRACT Even if many Vibrio spp. are endemic to coastal waters, their distribution in northern temperate and boreal waters is poorly studied. To identify environmental factors regulating Vibrio populations in a salinity gradient along the Swedish coastline, we combined Vibrio-specific quantitative competitive PCR with denaturant gradient gel electrophoresis-based genotyping. The total Vibrio abundance ranged from 4 � 103 to 9.6 � 104 cells liter−1, with the highest abundances in the more saline waters of the Skagerrak Sea. Several Vibrio populations were present throughout the salinity gradient, with abundances of single populations ranging from 5 � 102 to 7 � 104 cells liter−1. Clear differences were observed along the salinity gradient, where three populations dominated the more saline waters of the Skagerrak Sea and two populations containing mainly representatives of V. anguillarum and V. aestuarianus genotypes were abundant in the brackish waters of the Baltic Sea. Our results suggest that this apparent niche separation within the genus Vibrio may also be influenced by alternate factors such as nutrient levels and high abundances of dinoflagellates. A V. cholerae/V. mimicus population was detected in more than 50% of the samples, with abundances exceeding 103 cells liter−1, even in the cold (annual average water temperature of around 5�C) and low-salinity (2 to 4‰) samples from the Bothnian Bay (latitude, 65�N). The unsuspected and widespread occurrence of this population in temperate and boreal coastal waters suggests that potential Vibrio pathogens may also be endemic to cold and brackish waters and hence may represent a previously overlooked health hazard.
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Niu, Cen Cen, Qing Wang, Wen Hua Wang, Yan Ge Zhang y Cong Ye. "Research on Moisture Migration Experiment of Seasonally Frozen Zone Saline Soil". Advanced Materials Research 1065-1069 (diciembre de 2014): 168–71. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.168.
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Saline soil is widely distributed in Jilin seasonally frozen zone. Many engineering hazards are associated closely related to moisture migration with freezing-thawing cycles. Soil salinization in the region is mainly due to migration of soil moisture and salinity caused by the temperature gradient with soil freezing process in this area. Adopt self-developed experiment instrument for measuring the freezing experiments of saline soil in Sanzhigou. Constract and analyze the transformation of moisture content and soluble salt before and after the freeze, and quantify the moisture and salinity substance migration in the freezing process.
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González del Río, J., I. Romero, S. Falco, M. Rodilla, M. Saez, J. P. Sierra, A. Sánchez-Arcilla y C. Mösso. "Changes in Phytoplankton Population along the Saline Gradient of the Júcar Estuary and Plume". Journal of Coastal Research 10047 (septiembre de 2007): 63–68. http://dx.doi.org/10.2112/1551-5036-47.sp1.63.
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Duarte, B., D. Santos, J. C. Marques y I. Caçador. "Ecophysiological constraints of two invasive plant species under a saline gradient: Halophytes versus glycophytes". Estuarine, Coastal and Shelf Science 167 (diciembre de 2015): 154–65. http://dx.doi.org/10.1016/j.ecss.2015.04.007.
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Costa, Cínthia Maria X., Fernanda de Córdoba Lanza y Dirceu Solé. "Broncoprovocação com solução salina hipertônica em crianças asmáticas". Revista Paulista de Pediatria 30, n.º 3 (septiembre de 2012): 397–403. http://dx.doi.org/10.1590/s0103-05822012000300014.
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OBJETIVO: Verificar se o teste de broncoprovocação, com solução salina hipertônica a 4,5%, permite detectar o gradiente de resposta em crianças e adolescentes com asma, segundo a gravidade da enfermidade. MÉTODOS: Estudo transversal composto por 75 pacientes asmáticos com idades entre seis e 18 anos. Os pacientes foram classificados pela gravidade (intermitente associada à persistente leve - IL, e persistente moderada associada à grave - MG) e segundo a presença de sensibilização a aeroalérgenos (testes cutâneos de hipersensibilidade imediata a Dermatophagoides pteronyssinus, D. farinae e Blomia tropicalis) ou não (atópicos versus não atópicos). Todos foram submetidos ao teste de broncoprovocação com solução salina hipertônica a 4,5%, considerando-se o resultado positivo se havia redução do volume expiratório forçado no primeiro segundo (VEF1) ≥20%. RESULTADOS: 60 indivíduos eram atópicos. A frequência de positividade do teste de broncoprovocação foi maior no Grupo MG do que no IL (93 versus 65%). O tempo necessário para a queda de 20% do VEF1 para o grupo de atópicos foi menor no MG quando comparado ao IL: 90 (30 - 330) versus 210 (30 - 690) segundos, com p<0,05. A porcentagem de queda do VEF1 foi mais acentuada no subgrupo MG do que no IL [26,4% (14 - 63) versus 20% (0 - 60), p<0,05]. CONCLUSÕES: O teste de broncoprovocação com solução salina hipertônica a 4,5% é de fácil realização e seguro, permitindo detectar gradiente de resposta em crianças e adolescentes com asma segundo a gravidade da mesma. A maior frequência de positividade e a queda mais rápida do VEF1 foram observadas nos pacientes com asma moderada ou grave.
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Treppo, Steven, Srboljub M. Mijailovich y José G. Venegas. "Contributions of pulmonary perfusion and ventilation to heterogeneity in V˙a/Q˙measured by PET". Journal of Applied Physiology 82, n.º 4 (1 de abril de 1997): 1163–76. http://dx.doi.org/10.1152/jappl.1997.82.4.1163.
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Treppo, Steven, Srboljub M. Mijailovich, and José G. Venegas. Contributions of pulmonary perfusion and ventilation to heterogeneity in V˙a/Q˙measured by PET. J. Appl. Physiol. 82(4): 1163–1176, 1997. To estimate the contributions of the heterogeneity in regional perfusion (Q˙) and alveolar ventilation (V˙a) to that of ventilation-perfusion ratio (V˙a/Q˙), we have refined positron emission tomography (PET) techniques to image local distributions of Q˙ andV˙a per unit of gas volume content (sQ˙ and sV˙a, respectively) and Va/Q˙ in dogs. sV˙a was assessed in two ways: 1) the washout of 13NN tracer after equilibration by rebreathing (sV˙a i), and 2) the ratio of an apneic image after a bolus intravenous infusion of 13NN-saline solution to an image collected during a steady-state intravenous infusion of the same solution (sV˙a p). sV˙a p was systematically higher than sV˙a i in all animals, and there was a high spatial correlation between sQ˙ and sV˙a p in both body positions (mean correlation was 0.69 prone and 0.81 supine) suggesting that ventilation to well-perfused units was higher than to those poorly perfused. In the prone position, the spatial distributions of sQ˙, sV˙a p, and V˙a/Q˙ were fairly uniform with no significant gravitational gradients; however, in the supine position, these variables were significantly more heterogeneous, mostly because of significant gravitational gradients (15, 5.5, and −10%/cm, respectively) accounting for 73, 33, and 66% of the corresponding coefficient of variation (CV)2 values. We conclude that, in the prone position, gravitational forces in blood and lung tissues are largely balanced out by dorsoventral differences in lung structure. In the supine position, effects of gravity and structure become additive, resulting in substantial gravitational gradients in sQ˙ and sV˙a p, with the higher heterogeneity inV˙a/Q˙ caused by a gravitational gradient in sQ˙, only partially compensated by that in sV˙a.
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Wei, Mingdong, Arttu Polojärvi, David M. Cole y Malith Prasanna. "Strain response and energy dissipation of floating saline ice under cyclic compressive stress". Cryosphere 14, n.º 9 (4 de septiembre de 2020): 2849–67. http://dx.doi.org/10.5194/tc-14-2849-2020.
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Abstract. Understanding the mechanical behavior of sea ice is the basis of applications of ice mechanics. Laboratory-scale work on saline ice has often involved dry, isothermal ice specimens due to the relative ease of testing. This approach does not address the fact that the natural sea ice is practically always floating in seawater and typically has a significant temperature gradient. To address this important issue, we have developed equipment and methods for conducting compressive loading experiments on floating laboratory-prepared saline ice specimens. The present effort describes these developments and presents the results of stress-controlled sinusoidal cyclic compression experiments. We conducted the experiments on dry, isothermal (−10 ∘C) ice specimens and on floating-ice specimens with a naturally occurring temperature gradient. The experiments involved ice salinities of 5 and 7 ppt, cyclic stress levels ranging from 0.04–0.12 to 0.08–0.25 MPa and cyclic loading frequencies of 0.001 to 1 Hz. The constitutive response and energy dissipation under cyclic loading were successfully analyzed using an existing physically based constitutive model for sea ice. The results highlight the importance of testing warm and floating-ice specimens and demonstrate that the experimental method proposed in this study provides a convenient and practical approach to perform laboratory experiments on floating ice.
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Essa, Mohammed Hussain, Nuhu Dalhat Mu’azu, Salihu Lukman y Alaadin Bukhari. "Integrated Electrokinetics-Adsorption Remediation of Saline-Sodic Soils: Effects of Voltage Gradient and Contaminant Concentration on Soil Electrical Conductivity". Scientific World Journal 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/618495.
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In this study, an integrated in situ remediation technique which couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic clay soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil electrical conductivity. Box-Behnken Design (BBD) was used for the experimental design and response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained using Design-Expert version 8 platform. The total number of experiments conducted was 15 with voltage gradient, polarity reversal rate, and initial contaminant concentration as variables. The main target response discussed in this paper is the soil electrical conductivity due to its importance in electrokinetic remediation process. Responses obtained were fitted to quadratic models whoseR2ranges from 84.66% to 99.19% with insignificant lack of fit in each case. Among the investigated factors, voltage gradient and initial contaminant concentration were found to be the most significant influential factors.
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Bryanskaya, Alla V., Aleksandra A. Shipova, Alexei S. Rozanov, Oxana A. Kolpakova, Elena V. Lazareva, Yulia E. Uvarova, Vadim M. Efimov et al. "Diversity and Metabolism of Microbial Communities in a Hypersaline Lake along a Geochemical Gradient". Biology 11, n.º 4 (15 de abril de 2022): 605. http://dx.doi.org/10.3390/biology11040605.
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In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.
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Yang, Li E., Patrick K. K. Leong, Shaohua Ye, Vito M. Campese y Alicia A. McDonough. "Responses of proximal tubule sodium transporters to acute injury-induced hypertension". American Journal of Physiology-Renal Physiology 284, n.º 2 (1 de febrero de 2003): F313—F322. http://dx.doi.org/10.1152/ajprenal.00134.2002.
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Renal injury-induced by phenol injection activates renal sympathetic afferent pathways, increases norepinephrine release from the posterior hypothalamus, activates renal efferent pathways, and provokes a rapid and persistent hypertension. This study aimed to determine whether phenol injury provoked a redistribution of proximal Na+ transporters from internal stores to the apical cell surface mediated by sympathetic activation, a response that could contribute to generation or maintenance of hypertension. Anesthetized rats were cannulated for arterial blood pressure tracing and saline infusion and then 50 μl 10% phenol or saline was injected into one renal cortex ( n = 7 each). Fifty minutes after injection, kidneys were removed and renal cortex membranes from injected kidneys were fractionated on sorbitol gradients and pooled into three windows (WI–WIII) that contained enriched apical brush border (WI); mixed apical, intermicrovillar cleft and dense apical tubules (WII); and intracellular membranes (WIII). Na+ transporter distributions were determined by immunoblot and expressed as percentage of total in gradient. Acute phenol injury increased blood pressure 20–30 mmHg and led to redistribution of Na+/H+ exchanger type 3 (NHE3) out of WIII (from 22.79 ± 4.75 to 10.79 ± 2.01% of total) to WI (13.07 ± 1.97 to 27.15 ± 4.08%), Na+-Pi cotransporter 2 out of WII (68.72 ± 1.95 to 59.76 ± 2.21%) into WI (9.5 ± 1.62 to 18.7 ± 1.45%), and a similar realignment of dipeptidyl-peptidase IV immunoreactivity and alkaline phosphatase activity to WI. Renal denervation before phenol injection prevented the NHE3 redistribution. By confocal microscopy, NHE3 localized to the brush border after phenol injection. The results indicate that phenol injury provokes redistribution of Na+ transporters from intermicrovillar cleft/intracellular membrane pools to apical membranes associated with sympathetic nervous system activation, which may contribute to phenol injury-induced hypertension.